Animation of two seals flipping a ball back and forth. A lot of fun for a gifted group - if you'd like to compose your own then documentation is included in the ZIP files on how to produce animations on the calculator, and on the PC using the ADK (38G only).

Animation of two seals flipping a ball back and forth. A lot of fun for a gifted group - if you'd like to compose your own then documentation is included in the ZIP files on how to produce animations on the calculator, and on the PC using the ADK (38G only).

This aplet contains sets of bivariate data which have the same summary statistics but totally different 'shapes' when graphed. They illustrate the need to rely on more than just the stats when deciding on whether a linear model is appropriate!

This aplet contains sets of bivariate data which have the same summary statistics but totally different 'shapes' when graphed. They illustrate the need to rely on more than just the stats when deciding on whether a linear model is appropriate!

One of the most fundamental theorems in the study of statistical inference is the Central Limits Theorem. This states basically that the means of successive random samples taken from a population will be normally distributed whatever the underlying parent distribution. This aplet illustrates this and that the standard deviations are related by ratio. Sampling can be done from different parent distributions and the resulting collection of means compared to the equivalent Normal distribution. It is fairly slow to execute because of the need for repeated sampling but would be quite useful to teachers.

One of the most fundamental theorems in the study of statistical inference is the Central Limits Theorem. This states basically that the means of successive random samples taken from a population will be normally distributed whatever the underlying parent distribution. This aplet illustrates this and that the standard deviations are related by ratio. Sampling can be done from different parent distributions and the resulting collection of means compared to the equivalent Normal distribution. It is fairly slow to execute because of the need for repeated sampling but would be quite useful to teachers.

This aplet investigates the common charity game consisting of tossing of a coin onto a square grid. It requires only knowledge of quadratic functions and can be used at a number of levels: to illustrate the convergence of experimental values towards theoretical ones, to investigate fitting a quadratic curve to experimental data, and to introduce the idea of a probability function.

This aplet investigates the common charity game consisting of tossing of a coin onto a square grid. It requires only knowledge of quadratic functions and can be used at a number of levels: to illustrate the convergence of experimental values towards theoretical ones, to investigate fitting a quadratic curve to experimental data, and to introduce the idea of a probability function.

This is a copy of the Function aplet with an extra entry on the VIEWS menu which produces 'nice' scales. You may have noticed that the default plot view scale of -6.5 to 6.5 produces 'nice' step sizes of 0.1 when using the trace facility. This aplet will allow you to set whatever scale you choose and then correct it to the closest approximation which will still offer similar 'nice' trace values such as 0.2, 0.25, 2, 0.04 etc. It includes the ability to produce scales which are 'nice' fractions of pi for use with trig functions.

This aplet calculates and displays measures of central tendency and spread for data which has been grouped into intervals. The user puts the interval mid-points into C1, the frequencies into C2 and the aplet will display the mean, proportional median, lower and upper quartiles and various other values. The user can also perform calculations such as finding the values which cut off the top 15% of data, the middle 30% etc.

This aplet calculates and displays measures of central tendency and spread for data which has been grouped into intervals. The user puts the interval mid-points into C1, the frequencies into C2 and the aplet will display the mean, proportional median, lower and upper quartiles and various other values. The user can also perform calculations such as finding the values which cut off the top 15% of data, the middle 30% etc.

This aplet provides simple drill practice for students learning the laws of indices, with the option of including negative powers. It presents students with practice problems in correct mathematical layout and then allows them to enter the simplified answer. There are a wide variety of styles of problems. It will then tell them if they are right or wrong, offering a second chance if needed.

This aplet provides simple drill practice for students learning the laws of indices, with the option of including negative powers. It presents students with practice problems in correct mathematical layout and then allows them to enter the simplified answer. There are a wide variety of styles of problems. It will then tell them if they are right or wrong, offering a second chance if needed.

This aplet gives inferential statistics access for the 38G similarly to that of the 39/40G. The interface is not as smooth as the 39G version and there is no graphical view to aid in your judgment but it does the trick pretty well. Documentation is included.

An aplet similar to the Quadratic and Trig Explorers (but not as fast) which allows the student to explore linear graphs. The equation of the graph is displayed at the top left corner of the screen and the student can change the gradient and y-intercept using the arrow keys. Intercepts are shown on the screen.

An aplet similar to the Quadratic and Trig Explorers (but not as fast) which allows the student to explore linear graphs. The equation of the graph is displayed at the top left corner of the screen and the student can change the gradient and y-intercept using the arrow keys. Intercepts are shown on the screen.

This aplet visually solves linear programming problems, finding the vertices of the feasible region and the max/min of an objective function. The final stage of finding the vertices is a bit slow but the result is very impressive. It's a wonderful tool for teachers marking test papers - it lets you easily check whether a student's feasible region is correct if they have their constraints wrong. That's why I originally wrote it: sheer frustration after the 20th paper that had to be reworked from scratch to assign part marks.

This aplet visually solves linear programming problems, finding the vertices of the feasible region and the max/min of an objective function. The final stage of finding the vertices is a bit slow but the result is very impressive. It's a wonderful tool for teachers marking test papers - it lets you easily check whether a student's feasible region is correct if they have their constraints wrong. That's why I orginally wrote it: sheer frustration after the 20th paper that had to be reworked from scratch to assign part marks.

This is one of those "must have" aplets for students who solve problems involving borrowing money and making regular repayments. Once you have it on your calculator all you have to do is store the amount borrowed into P, the interest rate in to R and the amount being repaid into A and the aplet will then show you the remaining principal and interest charged each year/month/quarter.

A collection of music files, two of which are written by Colin Croft and the others by unknown programmers. Songs are: Flintstones, Dumped Again, Blister in the Sun, Mary Had a Little Lamb, Nick's Song, Happy Birthday, Charge, Funeral March, Come As You Are, The First Nowell, Happy Birthday (II), Star Wars, Hymn 389.

An essential tool for any student going into an exam which involves probability functions. This is two copies of the Solve aplet with equations pre-entered for Discrete and Continuous probability density functions respectively. Covers the Binomial distribution (individual and cumulative), the Poisson distribution (individual and cumulative), the Exponential function, the Normal distribution, plus more.

An essential tool for any student going into an exam which involves probability functions. This is two copies of the Solve aplet with equations pre-entered for Discrete and Continuous probability density functions respectively. Covers the Binomial distribution (individual and cumulative), the Poisson distribution (individual and cumulative), the Exponential function, the Normal distribution, plus more.

Very well written HP 38G Aplet. This allows students to investigate the behavior of the graph of y=a(x+h)2+v as the values of a, h and v change. This can be done both by manipulating the equation and seeing the change in the graph, and by manipulating the graph and seeing the change in the equation.

Given the coefficients of a polynomial of any degree, it will give you the roots to any desired number of significant figures. If one or more of the roots are complex then it will ignore those and give only the real ones.

Given the coefficients of a polynomial of any degree, it will give you the roots to any desired number of significant figures. If one or more of the roots are complex then it will ignore those and give only the real ones.

School activity designed to simulate sets of observations on various discrete and continuous random variables. These can be used in test problems or exercises, or as aids in teaching the topic of random variables.

School activity designed to simulate sets of observations on various discrete and continuous random variables. These can be used in test problems or exercises, or as aids in teaching the topic of random variables.

School activity designed to investigate the definitions of sine, cosine and tangent on the Unit circle. These can be used in test problems or exercises, or as aids in teaching the topic of random variables.

School activity designed to investigate the definitions of sine, cosine and tangent on the Unit circle. These can be used in test problems or exercises, or as aids in teaching the topic of random variables.

This is a collection of small programs you can type in yourself or download. They perform a multitude of small tasks, some that are so easy you'll wonder why I wrote a program for them, some that are really cool. Mostly math programs, for numeric, trigonometric, complex, linear, and cubic calculations, plus probability, matrix, finance, statistics, and more.

This is a collection of small programs you can type in yourself or download. They perform a multitude of small tasks, some that are so easy you'll wonder why I wrote a program for them, some that are really cool. Separated into two parts, because there are too many programs to fit all in the 38's memory at once. Mostly math programs, for numeric, trigonometric, complex, linear, and cubic calculations, plus probability, matrix, finance, statistics, and more.

School activity designed to easily and quickly analyze Time Series style data, by calculating moving averages (3, 4 & 5 point), seasonal residuals, trend lines and seasonally adjusted data. It more a working tool, rather than an investigative tool.

School activity designed to easily and quickly analyze Time Series style data, by calculating moving averages (3, 4 and 5 point), seasonal residuals, trend lines and seasonally adjusted data. It more a working tool, rather than an investigative tool.

You may be aware that one of the problems with the HP39G and HP40G is that whole rows or columns of keys will occasionally stop working. If you can still access the APLET view and the screen keys then this aplet will transfer you into the Program or Note views so that you can use SAVE/RECV to save them to a PC (assuming that you have a cable) before getting your calculator replaced.

This is an easy adaption of the Parametric aplet which allows the student to investigate geometric transformations using 2x2 matrices. It is a fantastic teaching tool - my class deduced all the basic 2x2 transformation matrices for themselves in less than an hour.

This is an easy adaption of the Parametric aplet which allows the student to investigate geometric transformations using 2x2 matrices. It is a fantastic teaching tool - my class deduced all the basic 2x2 transformation matrices for themselves in less than an hour.

This is a very neat practical joke program written by Cathy Edward's brother (slightly modified by Colin Croft). It puts a false picture of the HOME view on the screen and then no matter what key the person hits, it just puts up a message saying "Go away I'm busy!". Press ON two or three times quickly to get out.

Very well written HP 38G Aplet. This allows students to investigate the behavior of the graph of y=a sin(bx+c)+d as the values of a, b, c and d change. This can be done both by manipulating the equation and seeing the change in the graph, and by manipulating the graph and seeing the change in the equation.

Adjusts axes to nice values so cross-hair 'jumps' are to useful points rather than horrible decimals. Trig gives \pi fractions. Similar to Function Plus, but a program instead of an aplet, requiring less memory.